Composite polysaccharides and protein hydro-gels for controlled release applications: Formulation, characterization and release studies

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2023-1-26

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Özel, Barış

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Hydrogels are highly hydrophilic polymer gels with macromolecular three-dimensional networks. They can swell by absorbing and retaining large amount of water without dissolving and losing their integrity. Polysaccharides and proteins are commonly used for designing hydrogels to be used in food applications. Encapsulating bioactive agents is one of the common uses of these gels. Composite gels in which one or two polymers are blended to modulate the physicochemical properties of the gels have gained interest due to enhanced stability and release profiles. Pectin (PC), Gum Tragacanth (GT) and Xanthan Gum (XG) were the polysaccharides used for designing Whey Protein Isolate (WPI) based release systems in this study. Black carrot concentrate (BC) having a rich anthocyanin profile was encapsulated in these hydrogels. Release behaviors of the hydrogels were monitored in neutral pH phosphate buffer and simulated in vitro gastrointestinal tract (GIT) conditions. Nuclear Magnetic Resonance (NMR) Relaxometry was used as the main characterization technique to understand water-binding behavior of the polymers in different release media. Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), rheological and textural measurements of hydrogels were also conducted to characterize the hydrogels in detail. Polysaccharide blending retarded the release profiles in phosphate buffer (p < 0.05). Composite hydrogels also prevented whole release of BC in gastric phase and delivered some of the encapsulated material in intestinal phase. Especially GT and XG blended samples attained more gradual release profiles in GIT. Simple mathematical and kinetic models were used to define the release in the gel systems. In addition to controlled release experiments, BC loaded hydrogels were applied to whole-fat yogurt samples. Total phenolic contents and antioxidant capacities of the yogurt samples were monitored during four-week storage. Hydrogel blending to yogurt increased the total phenolic contents and antioxidant capacities of the samples. Hydrogels except for XG containing ones also preserved the total phenolic content and the antioxidant capacity of the yogurt during storage.

Subject Keywords

Hydrogel, Whey protein isolate, Pectin, Gum tragacanth, Xanthan gum

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https://hdl.handle.net/11511/101956

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

B. Özel, “Composite polysaccharides and protein hydro-gels for controlled release applications: Formulation, characterization and release studies,” Ph.D. - Doctoral Program, Middle East Technical University, 2023.